/Engine/Source/Runtime/GeometryCore/Public/DynamicMeshEditor.h
Weld together two loops of vertices. Loops must be oriented (ordered) correctly for your use case.
true if operation succeeded, false if any errors ocurred
bool WeldVertexLoops ( const [TArray](API\Runtime\Core\Containers\TArray)< int32 > & VertexLoop1, const [TArray](API\Runtime\Core\Containers\TArray)< int32 > & VertexLoop2 )